I have a newly rebuilt and bored out 455 that is going in my 69 GTO. I went with a slightly larger cam, new lifters, springs, ground down crank shaft, the works. I am replacing all the components that have anything to do with running through the engine. Fuel system, radiator, and Carb! I have narrowed down two carbs that I am debating on and am wondering if anyone has had any good or bad experiences with them. They are the Quick Fuel 750 Brawler or the Demon 750 Street Demon.

yes I believe they have the same features that matter, as far as adjustability. The SS series may have some billet metering blocks etc. Compare the features, but QFT carbs are super adjustable carbs and run great. I prefer them and parts are easy to get from QFT which is in Bowling Green Kentucky.

The QFT story is that Holley engineers wanted corporate to make changes and inprovements on carb adjustability, ez change of air bleed, PVCH, IFR etc. but could not get it through. So they left and started their own company QFT. They were very successful and lots of folks loved the new QFT. Holley then bought the Company.

That is how I heard it, I am sure there is some nuances to all that, but nevertheless. Holley is a great company and QFT is their subsidiary. EZ to get parts.

I put a 750 Street Demon on my 67 400 a while back...and my advice to you is...don't go there!..."off the line" It had a bog or pop I just couldn't tune out of it...even after dumping like 60.00 more on the dinky tuning kit...although, after the "bog" it roared and ran like gangbusters. Reading some buyers opinions, I found plenty of folks who were happy with it..but others had my same problem...it seems pump shot related...In short, do you wanna risk it?...plus it won't fit a drop base air cleaner without a spacer that makes it a bit too tall.
If it were really good, I'm sure we'd be seeing and hearing a lot more about how great it is by now.
Anyway, I just thought I'd share my particular experience with it. Good luck man!